1. Field of the Invention
The present invention relates to a data transfer method used in a display apparatus driving circuit for driving a display apparatus such as a flat display and, more particularly, to an improved data transfer method for a driving integrated circuit, which can reduce the average data transfer amount.
2. Related Background Art
Conventionally, data for one line must be transferred to a driving circuit of a flat display (to be referred to as an FPD hereinafter: Flat Panel Display) since the display operation on the FPD is performed by a line or dot sequential method. More specifically, in a conventional display, all the bits of display data must be transferred in synchronism with the frame frequency. Also, driving data of a driving integrated circuit is updated each time display data is transferred.
FIG. 1 is a physical schematic diagram showing the conventional data transfer method. The system shown in FIG. 1 includes a display apparatus (panel) 1, information line side driving integrated circuits (segment drivers) 2, segment bus boards 5, data buses 7, clock signal lines 8, serial data input signal lines 9, and a controller 10.
FIG. 2 is a schematic diagram of the segment drivers 2 in the conventional data transfer method shown in FIG. 1. The video data buses 7 for supplying video data ID0 to ID7 and the clock signal line 8 for supplying clocks (CLK) are connected in parallel with the segment drivers 2 (2-1, 2-2, 2-3, . . . ), and the serial data input signal (CSDi) line 9 is cascade-connected to these drivers 2. The first segment driver 2-1 receives a serial data input signal CSDi from the controller 10. A serial data output signal a output from the first segment driver 2-1 is connected to the serial data input pin of the second segment driver 2-2, and a serial data output signal b output from the second segment driver 2-2 is connected to the serial data input pin of the third segment driver 2-3.
FIG. 3 is a timing chart in the conventional data transfer method shown in FIG. 1. FIG. 4 is a block diagram showing the arrangement of the driver in the conventional data transfer method shown in FIG. 1.
The conventional data transfer method will be explained below with reference to FIGS. 1 to 4. As shown in FIG. 3, segment image data (video data) for all the drivers are serially transferred in an 8-bit width, and when first data, i.e., D0 to D7, of these image data are supplied, the serial data input signal CSDi simultaneously changes to xe2x80x9c1xe2x80x9d. Then, the first segment driver 2-1 shown in FIG. 2 begins to latch the input image data and simultaneously begins to count the number of clocks. When the segment driver 2-1 has counted 20 clocks CLK, it completes the data input operation, and sets the serial data output signal a to be xe2x80x9c1xe2x80x9d. Similarly, the second and third segment drivers receive image data in the same procedure as described above. With this operation, data D0 to D159 are received as image data of the first segment driver, data D160 to D319 are received as image data of the second segment driver, and data D320 to D479 are received as image data of the third segment driver, thus completing the transfer operation of image data for one horizontal scanning period.
However, in the above-mentioned prior art, since each driving integrated circuit has neither a latch memory nor a multiplexer circuit, sequentially transferred data are latched by a required amount (corresponding to the data holding performance of the integrated circuit), or data corresponding to a sub-scanning width are sequentially transferred using n driving integrated circuits via a shift register to form 1-line data.
Therefore, in the conventional data transfer method, even when a display apparatus with memory characteristics such as a ferroelectric liquid crystal display (to be referred to as an FLCD hereinafter: Ferroelectric Liquid Crystal Display) is to be driven, data for one line are transferred.
An object of the present invention is to provide a display apparatus wherein two kinds of informations are transmitted through a common bus in time series.
Another object of the present invention is to provide a display apparatus which can recognize an arrangement position even in case of using the same curcuit structure of IC.
The present invention has been made in consideration of the conventional problems, and has as its object to reduce the average data transfer amount from a controller to drivers in a display apparatus driving circuit. By reducing the data transfer amount, consumption power and radiation noise are expected to be reduced.
In order to achieve the above object, according to the present invention, in a data transfer method for transferring data to information-side drivers for driving a display apparatus, driver circuits each comprising a chip address/video data discrimination circuit and a unit driver are mounted around the display apparatus, each unit driver is set with its own chip address by means of a hardware pattern, and data exchange with the driver circuits is performed, so that chip address information and video data information are time-divisionally transferred to the target unit driver by utilizing a chip address/video data common bus line and a chip address/video data discrimination control signal.
According to a preferred embodiment of the present invention, the display apparatus comprises a flat display. Each driver circuit comprises an integrated circuit having the chip address/video data discrimination circuit and one unit driver. The unit driver comprises a chip address terminal consisting of a plurality of pins, which are used for setting its own address. Each unit driver comprises a latch means for holding previous data until it receives new data, and outputting data in accordance with the held data, and transfers data of only the unit driver whose video data has changed. In this case, the output pins of each unit driver are divided into a plurality of blocks, and data of only blocks whose video data have changed are transferred. Alternatively, only data between output pin blocks designated by start and end block signals of the output pins of each unit driver are transferred.
According to the present invention, when, for example, a segment-side driving integrated circuit comprises a latch circuit, a multiplexer circuit, and a chip address discrimination circuit to realize a data transfer method with control data, only changed data are transferred to the driving integrated circuit, thus reducing the average data transfer amount. More specifically, the driving integrated circuits for the flat display are mounted around the panel, and data exchange with the integrated circuits is performed so that a controller outputs data with address information and control information (driver output block information/start block information/end block information) to a target driving integrated circuit. In this manner, the integrated circuit can receive target data on the basis of the address information and the control information. Therefore, the controller designates only a position where data has changed and outputs the data thereto, thereby realizing the above-mentioned concept.
In the prior art, since chip select signals are required in units of chips, a large-screen, high-resolution display which is expected to be developed in future suffers an increase in the number of scanning lines, and the number of drivers increases accordingly, resulting in an increase in the number of signal lines.
According to an embodiment of the present invention, there is provided a data transfer method which can reduce the number of signal lines between a controller and drivers in a display apparatus driving circuit and has a predetermined number of signal lines independently of the resolution of a display apparatus.
According to another embodiment of the present invention, as scanning-side drivers for driving a display apparatus, unit drivers each comprising a chip address/pin address discrimination circuit are mounted around the display apparatus, each unit driver is set with its own chip address by means of a hardware pattern, and data exchange with the unit drivers is performed so that chip address information and pin address information are time-divisionally transferred to a target integrated circuit by utilizing a chip address/pin address common bus line and a chip address/pin address discrimination control signal.
In a preferred embodiment of the present invention, the display apparatus comprises a flat display. Each unit driver comprises a one-chip IC, which has a chip address terminal consisting of a plurality of pins. The chip address information is supplied to each driver by one or two clocks.
According to the embodiment of the present invention, integrated circuits each comprising, e.g., a chip address/pin address discrimination circuit are mounted around a flat display panel, each integrated circuit is set with its own chip address by means of a hardware pattern, and data exchange with the integrated circuits is performed so that chip address information and pin address information is time-divisionally transferred to a target driving integrated circuit by utilizing a bus line arranged around the panel. In this manner, the number of signal lines between a controller and drivers can be reduced, and the present invention can be applied to a panel having a higher resolution (a larger number of scanning lines) without increasing the number of signal lines between the controller and drivers.
In the prior art, as for the common side (scanning side), data are transferred by a method different from that for the segment side without using a common data line, and the controller must independently output segment data and common data, thus requiring a larger number of signal lines.
According to an embodiment of the present invention, the number of signal lines between the controller and drivers in a display apparatus driving circuit can be reduced, the number of signal lines does not depend on the resolution of a display apparatus, and the average data transfer amount from the controller to the drivers can be reduced.
For this purpose, according to the present invention, in a data transfer method for transferring data to drivers for driving a display apparatus, scanning-side drivers and information-side drivers are mounted around-the display apparatus, and data transfer to the scanning- and information-side drivers is performed using a common bus line which transfers information to both the scanning- and information-side drivers.
According to a preferred embodiment of the present invention, the display apparatus comprises a flat display. Each of the scanning- and information-side drivers comprises one or a plurality of one-chip integrated circuits, and each integrated circuit is set with its own chip address by means of a hardware pattern. For example, each integrated circuit comprises a chip address terminal consisting of a plurality of pins, and its chip address is set by fixing the respective pins to ground (GND) or VCC. Information to each scanning-side driver consists of chip address information and pin address information, and information to each information-side driver consists of chip address information and video data information. Each information-side driver has a data latch means for latching previous data until it receives new data, and outputting data in accordance with the held data. A controller transfers data of only the drivers whose video data have changed. The drivers are arranged at the four corners of the display apparatus, and the common bus is formed into a ring pattern.
According to an embodiment of the present invention, for example, each of segment-side driving integrated circuits comprises a latch circuit, a multiplexer circuit, and a chip address discrimination circuit, a common bus is used as segment/common lines, and data to be output from a controller have a common format so as to realize a data transfer method with control data, thereby reducing the number of signal lines between the controller and driving integrated circuits. At the same time, the controller transfers only changed data to the driving integrated circuits (in particular, segment-side ICs), thereby reducing the average data transfer amount. This method is particularly effective for a high-resolution display. More specifically, since driving integrated circuits for a flat display are mounted around the panel and data exchange with the integrated circuits is performed so that the controller outputs data with address information and control information to a target driving integrated circuit by utilizing a bus line arranged around the panel, the integrated circuit can receive target data on the basis of the address information and the control information. Therefore, the controller can designate only a position (arbitrary segment and common pin addresses) where data has changed and can output data thereto, thus realizing the above-mentioned concept.
In each conventional scanning-side driver, a pin address signal, a chip select signal, a waveform information signal, a mode set signal, and the like are transferred using independent signal lines. In each information-side driver, a video data signal, a waveform information signal, a test mode signal, and the like are transferred using independent signal lines. For this reason, the number of signal lines increases, resulting in an increase in cost and an increase in unnecessary radiation noise.
Since no latch memory for output control information is arranged, and an output control information signal line is connected in parallel with a plurality of drivers, identical waveform information can only be set in all the drivers.
Furthermore, since scanning- and information-side signals have independent signal formats, the number of signal lines further increases.
An embodiment of the present invention has been made in consideration of the conventional problems, and has as its object to reduce the number of signal lines that connect a controller and scanning- or information-side drivers to attain a cost reduction and a reduction of unnecessary radiation noise, and to transfer waveform information and the like in units of a plurality of drivers.
In this embodiment, data to be output from the controller to each scanning-side/information-side driver has a common data format, and chip address information, pin address information, waveform information, and mode set information for the scanning-side drivers, chip address information, video data information, waveform information, and test mode information for the information-side drivers, and control data for discriminating such information are time-divisionally transferred using a common bus.
With the above-mentioned data transfer method, the number of signal lines between the controller and drivers can be reduced, and at the same time, waveform information and mode set information can be independently transferred in units of drivers.
FIG. 5 shows the arrangement of a conventional matrix type display apparatus to which the above embodiment is to be applied. Referring to FIG. 5, the apparatus comprises a display unit 401 for displaying an image, driving circuits 402 for driving the scanning lines of the display unit 401, driving circuits 403 for driving the information lines of the display unit 401, a bus board 404 for supplying a power supply signal and a control signal to the driving circuits 402, a bus board 405 for supplying a power supply signal and a control signal to the driving circuits 403, a control means (to be referred to as a controller hereinafter) 406 for generating the power supply signals and control signals to be supplied to the driving circuits 402 and 403, a cable 407 for supplying the power supply signal and control signal generated by the controller 406 to the bus board 404, and a cable 408 for supplying the power supply signal and control signal generated by the controller 406 to the bus board 405.
The controller 406 determines the operations of the driving circuits 402 and 403 required for drawing an intended image on the basis of image information transferred from a computer or the like, and transfers data to the bus boards 404 and 405. More specifically, the controller 406 supplies control signals and power supply signals required for displaying the image to the bus boards 404 and 405 via the cables 407 and 408. The driving circuits 402 and 403 receive the control signals and power supply signals associated with the operations from the bus boards 404 and 405, and perform predetermined operations.
FIG. 6 shows the arrangement of general driving circuits. The same reference numerals denote the same parts as in FIG. 5, and a detailed description thereof will be omitted. Referring to FIG. 6, a data bus 409 transfers image data transferred from the controller 406. A clock signal line 410 supplies a clock signal for attaining synchronization of the reception timings of image data from the image data bus 409 to the driving circuits 403 and a clock signal for attaining synchronization of the operation timings in the driving circuits, i.e., for attaining synchronization of the operation timings of clock counters and latch circuits (to be described later). A chip select (to be abbreviated as CS hereinafter) signal line 411 supplies a CS signal for designating a driving circuit which is to receive image data. A drive signal line 412 supplies a drive signal used for simultaneously outputting image data to the display unit after image data for one line are received by all the driving circuits 403.
In the above-mentioned arrangement of the driving circuits, the number of CS signal lines for designating driving circuits which are to receive image data increases when the number of driving circuits increases upon realization of a large-screen or high-resolution display, and consequently, the number of control signals to be transferred from the controller increases. The increase in the number of control signals must be avoided as much as possible since it leads to an increase in unnecessary radiation noise.
This embodiment has been made to solve the above-mentioned problem, and provides a means for transferring image data to the respective driving circuits without increasing the number of control signals to be output from the controller, which problem arises upon an increase in the number of driving circuits.
In order to solve the above-mentioned problem, an image display apparatus of this embodiment comprises a display unit for displaying an image, driving circuits for driving the display unit, a bus board for supplying a power supply signal and a control signal to the driving circuits, a control means for generating the power supply signal and the control signal to be supplied to the driving circuits, and a transmission means for supplying the power supply signal and the control signal generated by the control means to the bus board. Data obtained by adding a signal, which indicates the start of transfer, to the beginning of image data transferred from the control means is transferred to the driving circuits, and each driving circuit comprises a circuit for recognizing its mounting position on the basis of a hardware pattern on the bus board.
According to this embodiment, even when the number of driving circuits increases, image data can be sequentially received in units of driving circuits without increasing the number of control signal lines, and the controller need not supply any chip select (CS) signal, thus obtaining an effect of suppressing unnecessary radiation noise, and the like.